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Respiratory diseases are the major group of diseases affecting poultry. Consequently, losses induced by these diseases are of major economic impact on the producer, the local economy and the U.S. economy. Many endemic respiratory infectious diseases in the U.S. continue to decrease the profitability of commercial poultry production. <P>
Viruses, bacteria and fungi cause respiratory diseases or interact to cause disease. Management of poultry is also a critical factor in controlling respiratory disease. <P>
One of the diseases, avian influenza (AI), has significant potential to impact the industry both in terms of animal losses and through export restrictions. AIV which is endemic in live poultry markets in the Eastern and Western U.S. will remain a significant threat to commercial poultry producers. A major AI outbreak occurred in commercial poultry in Virginia in 2002 resulting in $130 million in losses. Outbreaks in smaller commercial poultry populations occurred in Pennsylvania, Connecticut, Rhode Island, Minnesota, California, Delaware and Maryland. <P>
The U.S. poultry industry is the world's largest producer and second largest exporter of poultry meat. Approximately 16% of the total production in the U.S. is exported (Economic Research Service, USDA; . These export markets are subject to immediate restriction when poultry respiratory diseases such as AI or exotic Newcastle disease (END) are diagnosed and reported. <P>
Since our last project was initiated, important new threats to poultry production have become a concern of the industry and require a focus of our future project. A major epidemic of END occurred in California from September 2002-May 2003. Eradication of END cost more than $162 million, a value that does not include lost export trade at the time. Smaller outbreaks in non-commercial poultry occurred in Arizona and Nevada. An apparently unrelated END outbreak in backyard poultry also took place in Texas. <P>
OBJECTIVES: <OL> <LI> Identify reservoirs of infectious respiratory disease agents in wild birds and poultry. <LI> Develop improved diagnostic capabilities including real time PCR as well as other rapid on-farm tests for economically important respiratory diseases. <LI> Investigate the pathogenesis and polymicrobial interactions of specific infectious agents associated with poultry respiratory diseases (this includes interactions with underlying immunosuppressive agents).<LI> Develop new prevention and control strategies for poultry respiratory diseases.
NON-TECHNICAL SUMMARY: Poultry meat production has been continually increasing and consumption has surpassed all other meats. Because of the efficiency and competitive nature of the poultry industry, the cost of poultry meat is very attractive to consumers. Furthermore, the National Chicken Council released results of a survey showing that chicken was preferred to beef and pork, in terms of versatility, taste, ease of preparation, being healthful and nutritious, price and consistency of quality. In 2007, per-capita annual consumption of chicken was 90.6 pounds, the highest of any of the major meats. In addition, annual per capita turkey meat consumption was approximately 18 pounds. Beef consumption was 69 pounds per person on a retail weight basis, while pork was 52 pounds per person. A survey conducted by Bruskin Research found that 89% of the respondents ate chicken at least once per week and 36% of the respondents consumed chicken three times per week or more. The poultry industry is a highly integrated growth industry and is a major contributor to animal agriculture. The combined value of production from broilers, eggs, turkeys, and the value of sales from chickens in 2007 was $31.9 billion, up 24 percent from the $25.8 billion in 2006. Of the combined total, 67 percent was from broilers, 21 percent from eggs, 12 percent from turkeys, and less than 1 percent from chickens. In 2007, broiler production was valued at $21.5 billion up 21 percent from 2006. The number of broilers produced was 8.9 billion, slightly up from 2006. The value of turkeys produced during 2007 was $3.71 billion, up 4 percent from the $3.57 billion the previous year. Turkey production in 2007 totaled 7.87 billion pounds, up 5 percent from the 7.46 billion pounds produced in 2006. Chicken eggs are an important source of high quality protein and other nutrients in the diet. Control of respiratory infectious diseases lends itself to collaborative multistate research. The diseases are endemic in many poultry producing states. Furthermore the challenges posed by the number of different disease etiologies and their complexities require a multistate effort. The overall impact of a successful outcome will be improved diagnosis and control of respiratory diseases that will benefit the poultry industry. Impact of the research will be derived from identification of disease agent reservoirs such as wild birds, factors involved in agent transmission to poultry, the development and delivery of differential immuno- and gene-based diagnostics, determination of infection status, rapid strain identification, evaluation of vaccines, and the design and implementation of eradication protocols for selected agents. The overall outcome of the project is to produce findings that enable poultry industry to remain competitive and profitable.
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APPROACH: AIV surveillance will be performed in commercial poultry, backyard poultry, live bird markets and auctions, wild aquatic birds, and swine. AIV will be detected by virus isolation real-time RT-PCR. The survivability of AIVs in poultry litter at different times, temperatures, and litter moistures in the poultry house environment will be examined. The susceptibility of guinea fowl, turkeys, domestic ducks, and geese to AIVs from wild bird reservoirs will be determined. ILTV surveillance will be performed. Methods for AIV detection will be evaluated. AIV H5 LPAI isolates of wild bird origin will be characterized in chickens, ducks and turkeys. The potential for interference between ILTV, NDV and IBV live vaccines in chickens will be investigated. The genetic relatedness and pathogenicity of selected field isolates of respiratory viruses and mycoplasmas will be studied in chickens. Molecular determinants and mechanisms of NDV pathogenesis will be identified. Functions of genes in viral replication and pathogenesis will be investigated using a chimeric virus. Then safe live vaccines with genetic elements of more recent isolates will be engineered. Isolates will be obtained from surveillance of wild birds and live bird markets to identify contemporary NDV strains. The isolates will be characterized by sequencing, characterizing their virulence in poultry, and creating a database linking geographical, temporal, and biological data to the genomic information. In-house composting to inactive AIV will be studied. Vaccine will be characterized with wild type viruses in vitro, chickens and turkeys. The H, N, and M genes of AIV will be used to develop DNA-based and vector-based molecular vaccines. The protection of a replication-defective adenovirus recombinant vaccine. Research has shown the vaccine protected chicks vaccinated in ovo and day of age against HP H5 AIV. A transgenic yeast vaccine (for drinking water vaccination) expressing the HA from a LP AIV (duck isolate) will be developed. AIV antibody HI titers of chickens given the experimental yeast vaccine will be compared to titers of chickens given a commercial inactive vaccinated. A safe and effective recombinant APV vaccine will be developed. Recombinant APVs will be generated entirely from cloned cDNA based on independent mechanisms of attenuation. Vaccine candidates will be evaluated for their ability to protect turkeys vs. APV challenge. The efficacy of recombinant IBV DNA vaccines to protect chickens against heterologous strain challenge will be evaluated. The pathogenicity of selected IBV field isolates (novel S1 gene variants) for commercial broilers will be determined as well as the potential protective efficacy of live virus vaccines in challenge of immunity trials. On farm methods for reducing ILTV contamination will be developed including; poultry house heating, windrow composting, litter treatments, and insect control. Methods will be developed for reducing biofilms in drinkers which may harbor ILTV. Swabs taken from artificially ILTV adulterated dust, litter, drinkers and darkling beetles (adults and lesser meal worms larvae) will be tested by virus isolation/rPCR.